1) Field of the Invention
The present invention relates to an improvement in the apparatuses for developing films, particularly movie films.
More specifically, the invention relates to a new solution for an element of apparatuses of the above kind allowing to obtain a better development quality, beside a higher efficiency of the development of the same films.
2) Description of the Prior Art
At present, movie films are developed within very big apparatuses providing a dark room, a series of treatment rooms, within which the film is subjected to various treatments, such as fixing, washing, drying, etc.
The film, the length of which varies and in any case is noticeable, is wound about vertical frames, placed side by side each other within the various rooms., each one of said frames providing a series of vertical turns of the film, said film advancing mechanically dragged, up to the exit of the apparatus and to the winding about the final spool.
After the initial charging, the film advances along the apparatus, passing from one frame to the other one, without any interruption, through the various turns, passing from a treatment room to the following one. The number of turns per each frame and the number of frames for each room can be different according to the specific needing.
In order to properly advance, maintaining the correct orientation, turns of the film must be put under tension at the bottom in order to allow a proper advancement of the same film.
In the apparatuses of this kind presently used, tensioning of the film is obtained providing at the bottom of each turn a suitably sized weight. Being the number of turns provided in each apparatus very large, it can be easily understood both the complexity of this kind of solution, and the weight that every apparatus provides just for the presence of these weights.
Beside this particular, it must be considered that the optimum tension of the film varies in function of each single development speed, since the higher is the speed and higher must be the tension to which the film must be subjected.
Obviously, in an apparatus providing the tensioning by a weight for each single turn, once chosen the weight to be used, it is neither thinkable nor realisable to change the weight in case it is wished to vary the production speed.
Moreover, just for the same reasons, the weight will be suitable for the speed operation of the apparatus, but it will be not suitable for example at the start or in case of operation at a speed reduced with respect to the programmed speed, with consequent potential buckling of the film, which is subjected to an undue load.
All the above has heavy consequences on the productivity of the apparatus, mainly with reference to the quality of the product, to the flexibility and to the production rate.
In view of the above, the Applicant has realised an improvement in the apparatuses for developing films, particularly movie films.
Main object of the present invention is that of realising an improved apparatus for developing movie films providing a turns tensioning system for the various frame which is extremely simple under a constructive point of view.
Another object of the present invention is that of providing a solution of the above kind which allow to freely modify the tension of the turns of each single frame, in such a way to adapt the speed to the wished production speed, to the specific step to which it is subjected, thus optimising the apparatus operation.
Still another object of the present invention is that of providing an improved apparatus of the above kind that allows to avoid to subject the film to undue stresses.
These and other results are obtained according to the present invention proposing an apparatus for developing films, particularly movie films, wherein the tensioning of the single turns of each frame is obtained by a pneumatic piston, or equivalent means, the loading of which can be adjusted, for each frame, in function of the specific needing.
It is therefore specific object of the present invention an improved apparatus for developing films, particularly movie films, comprising a plurality of substantially vertical frames, for supporting and winding the film, placed within the different treatment rooms, each one of said frames providing a plurality of transmission turns for the film, each one of said turns substantially comprising an upper pulley and a lower pulley, and tensioning means of the film acting on the lower pulley, said apparatus being characterised in that said tensioning means of the film in the single turns are comprised of piston means, provided under the lower pulley of said turn, a single feeding system being provided for the piston means of each frame.
According to the invention, it can be provided one of said piston means for each turn of the frame.
Still according to the invention, it can be provided a piston for a group of turns, said group of turns could be comprised of two or more turns.
Furthermore, according to the invention, said piston can be a pneumatic, hydraulic, oleodynamic, oleopneumatic, etc. piston, preferably a pneumatic piston.
In a particularly preferred embodiment of the apparatus according to the invention, said tensioning means of the film comprise a block, within which a chamber for the primary air and a chamber for the secondary air are realised, a frame, supporting each lower pulley of the turns, vertically slidable with respect to said block, and pneumatic piston means, preferably, but not exclusively, one piston means for each turn, placed between the lower part of said frame and said block, in such a way to act as traction on the lower pulley of the turn.
Still according to the invention, valves are provided on said air primary and secondary chambers.
Furthermore, according to the invention, a protection bellow can be provided on said piston means.
Always according to the invention, said lower pulley is oriented with an angle with respect to the upper pulley.